The average thickness of the No. 7 coal seam is 9.5 m in Hami Mine, with simple structure, stable mining and shallow buried depth. Moore - Coulomb theory was used to study the effect of the seam strength to the top coal caving. The formula method and analogy of the height for overburden failure theory was used to calculate the fully mechanized caving height of overburden rock damage. And the FLAC3D numerical simulation was used to analyze mechanized coal caving to the No. 7 coal seam. The caving performance of the top coal in the first mining area was studied, the caving technology program could be performed, and the technology provided the mainly the solutions to technical problems.